1. Field of the Invention
The present invention relates to a vehicle electrical-load limiting apparatus for restricting, as needed, the driving of each of a plurality of electrical loads which are employed in a vehicle having an electric source mounted thereon such as a battery whose residual capacity is reduced with the elapse of time or a generator which needs another driving energy, and particularly employed in an electric automobile free of an internal combustion engine serving as a power source for its running or a hybrid-type electric automobile.
2. Description of the Related Art
In an electric vehicle having an electric motor serving as a power source, for example, the running distance is influenced by the residual capacity of a battery serving as an electric source for driving the electric motor. Therefore, there has been a demand for a battery having a capacity which can be increased as much as possible under conditions required for the electric vehicle. However, a battery capable of sufficiently providing, at one charge level, a running speed and a travelling distance of the electric vehicle, which are not inferior to those of a conventional engine-driven type automobile, has not yet been put to practical use. Even when a generator is mounted on a vehicle, it is important to ensure electrical energy for stably driving the generator for a predetermined period of time or longer.
Therefore, a technique for restricting the use of electrical loads, i.e., various electrical equipment or components mounted on a vehicle, which are activated by electrical energy supplied from an electric source mounted on the vehicle, in accordance with the conditions of the electric source, has been proposed with a view toward making a coverable or running distance longer by using an electric source such as a battery whose capacity is restricted.
In order to prevent an electric vehicle or the like from being incapable of reaching an intended place or a location at which a battery can be charged or replaced with another when the residual capacity of the vehicle battery is reduced, for example, there has been known a technique for restricting the driving of electrical components which are less important to the vehicle (or its driver) (see Japanese Utility Model Application Laid-Open Nos. 63-40135, 63-61360, for example). According to the disclosed technique, the electrical components (electrical loads) mounted on the vehicle are classified according to their importance. Priority given over the electrical components, for restricting the driving of the electrical components for each classification is then determined, and the groups of the electrical components whose driving is restricted are determined depending on the remaining capacity of the electric source mounted on the vehicle.
In the above disclosure, however, the driving of the electrical components is limited by quantitative restriction rules referred to as the classifications determined depending on the values of the residual capacity of the electric source. Therefore, a change in the classification of the electrical components whose driving is restricted occurs even if the values of the remaining capacity of the electric source vary slightly, so that inconvenience, i.e., unsuitable electrical load control such as a restriction beyond need, etc. tends to develop in practice. In order to perform the electrical load control suitable to practical use, it is necessary to judge or determine to what degree the driving of the electrical components should be restricted depending on how much the remaining capacity of the electric source is present and to carry out a fine drive restriction based on the result of the determination. The above disclosure has, however, the problem that the above determination and the drive restriction have not been taken into consideration.